Let $P\left( r \right) = \frac{Q}{{\pi {R^4}}}r$ be the charge density distribution for a solid sphere of radius $R$ and total charge $Q$. For a point $P$ inside the sphere at distance $r_1$ from the centre of the sphere, the magnitude of electric field is
zero
$\frac{Q}{{4\pi {\varepsilon _0}r_1^2}}$
$\frac{{Qr_1^2}}{{4\pi {\varepsilon _0}{R^4}}}$
$\frac{{Qr_1^2}}{{3\pi {\varepsilon _0}{R^4}}}$
Two large, thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and of magnitude $17.0\times 10^{-22}\; C/m^2$. What is $E$:
$(a)$ in the outer region of the first plate,
$(b)$ in the outer region of the second plate, and
$(c)$ between the plates?
A charge $Q$ is uniformly distributed over a large square plate of copper. The electric field at a point very close to the centre of the plane is $10\, V/m$. If the copper plate is replaced by a plastic plate of the same geometrical dimensions and carrying the same charge $Q$ uniformly distributed, then the electric field at the point $P$ will be......$V/m$
A conducting sphere of radius $10 \;cm$ has an unknown charge. If the electric field $20\; cm$ from the centre of the sphere is $1.5 \times 10^{3} \;N / C$ and points radially inward, what is the net charge (in $n\;C$) on the sphere?
An electrostatic field in a region is radially outward with magnitude $E$ = $\alpha r$ , where $\alpha $ is a constant and $r$ is radial distance. The charge contained in a sphere of radius $R$ in this region (centred at the origin) is
In the figure, a very large plane sheet of positive charge is shown. $P _{1}$ and $P _{2}$ are two points at distance $l$ and $2 \,l$ from the charge distribution. If $\sigma$ is the surface charge density, then the magnitude of electric fields $E_{1}$ and $E_{2}$ at $P _{1}$ and $P _{2}$ respectively are